Boiler return trap



PNE 301, 1935.. J. M DOUGHERTY BOILER RETURN TRAP Filed June 22, 1954 ZI A9 Patented pr. 30, 193g UNITED STATES PATENT oFFlcE 1,999,687 BoILER RETURN TRAP John M. Dougherty, st. Louis, M0. Application June 22, 1934, Serial No. 731,826 14 claims. (o1. 10s-252) My invention relates to automatic boiler return devices for low pressure steam heating or like systems wherein steam is alternately admitted to a vacuum return tank and condensed therein to exhaust air from the system and, in some installations, to pump water of condensa; tion from the radiators to the boiler.

The main object of my invention is to drive all the air from the vacuum condensation tank before condensing the steam therein to draw air or water from the system.

Another lobject ofV my invention is to reduce the amount of vacuum or power required for retem, -to the boiler. v

Another object of my invention is toraccelerate the condensation of steam in the vacuum condensing tankby exposing the same to contact with water of lower temperature than water which has been in contact with the steam.

In the accompanying drawing which illustrates a selected construction embodying the inventionf Figure 1 is an elevation and section Vcfa con- V densing-tank and equipment associated therewith embodying one form ofrmy invention.

Figure -2 is a detail of the thermostatic control and the air relief valve structurewhereby one source of supply of steam into the condensing tank is controlled.

"Figure 3 is a detail of the steam valve actuated by the thermostatic control.

In the construction illustrated, the vacuum condensing tank is shown at I. Piping 2 leads and includes an upstanding portion 3 having an open end 4 spaced a short distance'from the top of tank I and substantially above the highest water level reached Vin the tank. Piping 5 leads from the lower portion of tank I to the boiler (not shown) and piping 5 is substantially larger than piping 2. Pipe 6 between piping 2 and 5 provides for complete circulation in ther heating system independently of the vacuum tank structure. Check valves l, 8 and 9 permit water and steam to flow freely Ain the directionsindicated by the arrows A, B and C, respectively, and positively prevent the'ilow of fiuid in the'opposite direction.' A pressure check valve V is located f at the inlet end of piping 5 and closes against movement of fluid into the tank therethrough.

A relatively small cooling chamber I 0 is located adjacent the left hand end of tank I and is connected therewith by a series of pipes II disposed at different levels. A `series of flues F turning the.condensation, drawn from the sys-4 S direct to the tank. Valve 2| is of familiar form from the heating system (not shown) to the tank extend through tank I and chamber It and the passage of air through these flues is controlled by a damper D.

A thermostatic regulator device I3 is mounted on chamber Il) and is exposed to the temperature '5 therein. Member I3 is of well known construction and includes a bellows which expands when heatedto move nger I 4 upwardly. This raises the left hand portion of a lever Il pivoted at I8. A spring actuated air relief valve I2 on chamber I0 is controlled by lever I'I to which Vit is connected by link I2a.

A valve I5 controls the passage of steam from` a pipe yS through a pipe I9 to a perforated pipe 20 which is disposed vertically near the right hand end of the boiler and discharges steam thereinto at diierent levels substantially throughout the depth of the boiler. Valve I5 is connected by an arm I6 to the end of lever Il.

When the regulator finger I4 moves upwardly, lever I'I positively closes air relief valve IZ- and also closes steam valve I5. At the same time, lever I l opens the damper D, permitting the flow of air into flues F extending through chambers IIJ and tank I. A flue F leads from the right hand end of tank I to the chimney, thereby creating a draft through the lues.

Another steam inlet valve 2i functions independently of valve I5 to admit steam from pipe and is controlled by a weighted arm 22 actuated by a lloat 23 which rises and falls with the water level in condensing tank I. When float 23 rises, valve 2| is opened. When oat 23 falls, valve 2| is closed. An air relief valve 28 functions auto- 35 matically to vent air which may gather in the tank. Another air relief valve 2A functions similarly to vent air from the return system.

Operation:-Assu.me that the boiler is cold and tank I is lled with air. The bellows in the regulator I0 is contracted and finger I is in its lowermost position. Air relief valve I2 and steam valve I5 are open and steam valve 22 is closed. When the boiler is lired, the rst steam generated will pass through valve I5 and pipe I9 and be 45 discharged at 2B at the right hand end of the tank and will force the air therein to the left through tubes II into chamber I0 and out of air relief valve I2 until tank I is filled with steam,

when the same will contactY with the bulb in 0*' thermostatic device I3, expanding the bellows and shifting lever Il which closes air relief valve I2 and steam Valve I5 and opens damper D, all

as described-above.

YTheV steam in the tank being exposed tothe 55 room temperature will condense, creating a partial vacuum in the tank which draws water through pipe 3 into the tank until the water level in the tank raises oat 23 sufficiently to open valve 2 I. This will admit a fresh supply of steam to the tank, placing the same under boiler pressure which will close check valve 'I and open valves V and 8, and the water in the'tank will be forced into the boiler.

As the water level in tank I falls, float V23 is lowered until valve 2i snaps to closed position, the tank being substantially filled with steam which then condenses, creating a partial vacuum resulting in the closing of valve V and the opening of valve 'l and the drawing in of any additional supply of water through piping 3. As the water level rises, lifting iioat 23, the cycle ofr 'operations is repeated. f

The check valve V at the entrance to pipe 5 insures that the vacuum in tank I will draw'water from pipe 3 exclusively. That water will be'sub-V stantially cooler than the water in pipe 5 and this results in more rapid condensing of the steam and a higher degree of vacuum than .would result if water from pipe 5, previously heated by the steam in tank l, was drawn into the vacuum tank. 'I'he extension of pipe 3 to the upper part of the tank provides that all of the water drawn into the tank will contact with the steam before being heated by the water previously admitted which has vhad its temperature raised by the steam. This contributes to more rapid condensation of the steam in the tank throughout the period water is being admitted.

By making the water inlet piping 3 of smaller diameter than the piping 5 leading to the boiler,I a diiferential is created which facilitates the raising of the water through pipingv 3, by reducing the weight to be overcome, and facilitates the discharge to the boiler, by increasing the rate of flow from the tank.

By delivering the steam at the farend of the condensing tank i and at the varying levels, the-` steam'lls the tank, forcing all the air in theV tank ahead of it out through the cooling` chamber I0, but the steam does not come in contact with the regulating device E3 until the condensing tank I is entirely free of air, and when the steainqdoes come in Contact with the regulating device-it brings the regulator into operation to close off ther steam valve I5, and with the same actionto;clasel oi the atmospheric air valve I2, preventing al waste of steam. Y

The device may be applied to a heating system.v in which the vacuum tank is applied to the air line leading from the radiator toy acceleratetncpassage of steam from the boiler and to drawy water into the lower portion of the boiler rather than to pump it into the boiler under steam pressure. The function of the device is somewhat different but the operation is very similar.

Piping 5 will be discarded and piping 3 will bev connected to the line leading from the air valves on the radiators. Valve 2t and its float controlY will be omitted. In starting operation, the rst steam admitted to the tank will drive out the air therein through valve I2. When the steam reaches regulator I3 it closes valves IZYand I5.Y The steam in the tank then condenses, drawing air in from the heating system which will tend to cool the bulb in the regulator I3, resulting in shifting lever I'F so as, to open. steam. valve I5` and air relief valve I2. The boiler pressure will close valve I which will remain closed. until` suicient steam is present in tank I and chamber I0 to heat the thermostatic regulator to again shift lever I1 to close valves I2 and I5.

Repetition of this cycle exhausts the air in the heating system and draws water into the boiler through the water return line which is directly connected to the boiler below the water line.

Each of the installations described embodies the widely spaced arrangement of the steam inlet and air relief and thermostatic regulator. and the separate chamber for the latter, and utilizes the simultaneous mechanical closing of the air relief and steam inlet valves.

The details may vary other` than as described without departing from the spirit of the invention and I contemplate the exclusive use of those modifications which come within the scope of my claims.

I claim:

1.' In a structure of the class described, a condensing tank, means for admitting Water to said tank and for discharging water therefrom, means for supplying steam to said tank at one end thereof, an air relief valve, and a thermostati device for controlling said valve, said valve and device being located adjacent the opposite end of said tank.

2. In a structure of the class described, a condensingA tank, means for admitting Water to said tank and for discharging water therefrom,L means..

densing tank, means forV admitting water tank and for discharging water therefrom, means for supplying steam to said tank, seid meenam-, cluding a steam valve, an air relief vaailve,v anda thermostatic device for closingv andopeningboth of said valves simultaneously. l

4. A ,de-vice asrdescribedin claim 3 which. includes a secondmeansy for supplying steam tothe tank, a valve4 therefor, and a float in the tank for opening and closing said latter-mentioned valve according to the water Alevel thev tank and independently of the operation of the ther-- mostatic device.

densation tank, means for admittingrwater tosaid tank and for discharging water therefrom, -a substantially smaller chamber spaced from one end of said tank, tubes providing restrictedzpassages between said tank and. chamber, athermostaticregulator device adjacent to said chamber andy connected therewith, a. steam-pipeY discharging into the other end of said: tank, and a valve controlled bysaid regulator for said pipe. y y l 6.. A structure as described: in claim 5,` whiche also. includes an air relief valveleading from the smaller chamber, and means actuated by the regulator device for positively closing said. air relief valve as the. steam valve is closed. y Y

7. In astructure of4 the class: described, a conf d ensation-A tank, means for admitting water to.A

ing the functioning of said regulator unti-L said.

-Y Y h7l# tankisifreedot air..

50i' 5,. In a structure, of the class described.,VA a con- 8. In a structure of the class described, a condensation tank, means for admitting water to said tank and for discharging water therefrom, a chamber spaced from one end of said tank, an air relief valve and a thermostatic regulator in said chamber, said chamber being substantially smaller in volume than said tank but substantially equal to said tank in depth, there being a plurality of tubes disposed at different levels and forming restricted passages between said tank and chamber.

9. In a structure of the class described, a condensing tank, means for admitting water to said tank and for discharging Water therefrom, a supplementary chamberspaced therefrom, means for supplying steam to said tank, and a thermostatic device actuated by the presence of steam in said chamber for shutting olf the flow of steam to said means.

10. In a device of the class described, a condensing tank, means for supplying steam to said tank, means for admitting water to said tank and for discharging water therefrom, a thermostatic device spaced from said tank and arranged to shut off said means, and means for conducting steam from said tank to said thermostatic device only after said tank has been substantially filled with steam.

11. In a structure of the class described a condensation tank, means for admitting Water to said tank and for discharging Water therefrom, means for supplying steam to the interior of said tank adjacent one end thereof, a thermostatic device spaced outwardly from the other end of said tank, and means for conveying steam from the latter-mentioned end of said tank to said dev1ce.

12. In a structure of the class described, a condensation tank, means for admitting water to said tank and for discharging water therefrom, a separate chamber spaced outwardly from one end of said tank, a thermostatic device mounted on said chamber, an air relief valve mounted on said chamber, a valve for admitting steam to said tank, and an arm actuated by said thermostatic device when the latter is heated for simultaneously closing said air relief valve and said steam valve.

13. In a structure of the class described, a condensing tank, means for admitting water to said tank and for discharging water therefrom, a. steam supply pipe provided with an orice device arranged to discharge steam substantially throughout the depth of said tank at one end thereof.

14. In a structure of the class described, a co1)- densing tank, means for admitting Water to said tank and for discharging water therefrom, a steam supplly pipe extending downwardly into said tank at one end thereof and perforated to discharge steam into said tank at different levels substantially throughout its depth.

JOHN M. DOUGI-IERTY. 

